"While I acknowledge there will be an impact on some local business and service provider staff, these closures bring significant financial savings for the Government and the Australian taxpayer.

"The savings, which amount to at least $7.4 million a month, comprise the costs payable to the detention services provider, infrastructure and leasing arrangements and detention contractual arrangements."

Mr Morrison says the four facilities were never meant to be permanent.

Serco, which operates nine detention centres and four alternative places of detention, has contracts with the Immigration Department which are due to expire later this year, according to the company's website.

The Government has been reviewing the future of Australia's various detention centres as it aims to divert all new boat arrivals offshore.

The Greens' Immigration spokeswoman Sarah Hanson-Young says she's concerned about where the asylum seekers will be moved to.

"Christmas Island is already crowded; Manus Island and Nauru are not fit to hold anybody, let alone more people," she said.

"Mr Morrison needs to be upfront with the Australian people about exactly where people in those camps are going to go."

Closure to have economic impact on communities

The Mayor of Brighton, in Tasmania, says the closure of the Pontville detention centre will be an economic blow to the community.

Mayor Tony Foster says he is also angry that the Federal Government did not inform him of the decision before announcing it.

"Somewhere between 45 and 48 [staff] were able to service the centre while it was open, so that business is no longer there," he said.

"Very disappointing, disheartening ... there's been no consultation. I think it is absolutely just the way that this Government is treating the whole of Australia at the moment."

Tanya Browning, the acting chief executive of the Western Australia's shire of Leonora, says the decision to close the detention centre in her town is disappointing.

But she says it has not come as a complete surprise.

"We certainly will miss some of the staff that are here, especially those that have chosen to make Leonora their home," she said.

"That's a loss that certainly will be felt.

"Fortunately our community is very resilient. We are prepared for those types of events, [like] when mines close, and we might have a loss of a number of people within the community."